The present invention relates generally to power driven winches of the type having internal planetary gears for driving the cable drum. In one embodiment, the invention relates to a winch having an internal friction clutch mechanism for selectively connecting and disconnecting the cable drum to the power input.
Winches using one or more sets of planetary gears to transfer torque from a power input (e.g., winch motor) to the cable drum are well known. Further, it is known to provide an internal clutch mechanism in such winches for selectively connecting and disconnecting the cable drum to the winch motor whereby, for example, the clutch can first be disengaged to allow cable to be unreeled from the drum without operating the motor, and then the clutch can be engaged to allow the motor to power the drum for reeling in the cable against the load. Where it is desirable for the drum clutch mechanism be gradually engaged and disengaged while under load, the clutch mechanism must be of the type known as a friction clutch.
Heretofore the use of internal drum friction clutch mechanisms, especially those used in high-capacity winches, for example winches used on earth-moving machines, construction equipment or heavy trucks, has presented certain disadvantages. The reduction gear train of such winches includes multiple stages of planetary gears which take up a considerable amount of space. Typically, the drum friction clutch mechanism is located at a gear stage close to the cable drum where the torque it must transmit is relatively high, and as a result, the clutch mechanism must be physically large (e.g., large diameter) to handle the high torque requirements without failing or wearing prematurely. A first disadvantage of previous designs is that the size of such high-torque friction clutches is sometimes so large that it increases the overall size of the winch, either requiring the diameter of the winch housing to be increased, or requiring the clutch to be located to one side of the cable drum, thereby increasing the overall width of the winch. Obviously, this increased size can make it much more difficult to mount a high capacity winch on existing equipment. A second disadvantage of previous designs is that the large size and/or complexity of the high-torque friction clutches results in higher cost for their components and manufacture, consequently raising the cost of the associated winch. This of course, puts the manufacturer at a competitive disadvantage.
A need therefore exists, for a winch having a design which minimizes the size of the internal drum friction clutch to reduce the overall size of the winch. A need further exists, for a high-capacity winch with internal drum friction clutch having a simplified design which reduces the costs of manufacturing the winch.
The present invention disclosed and claimed herein comprises, in one aspect thereof, a winch including a drum rotatably mounted on a housing for winding a cable thereupon. A motor is attached to the housing, the motor supplying torque through a motor shaft. A special stage of planetary gears is mounted to the housing for transmitting torque between the motor shaft and the drum. The special stage of planetary gears includes a sun gear for receiving torque, a carrier/clutch unit and an annular ring gear encircling the carrier/clutch unit. The carrier/clutch unit includes a frame rotatably mounted to the housing and having walls defining a cavity therein, at least one circumferentially-spaced planet gear rotatably mounted on the frame for simultaneously engaging the sun gear and the ring gear, a selectively engagable clutch mounted within the cavity of the frame, and an output member which, when the clutch is engaged, can receive useful torque from the frame and, when the clutch is disengaged, cannot receive useful torque from the frame.